Process of filtering slimes.



Patented June 16, 19M

WITNESSES X5: AITORNZS G. BUTTERS. PROCESS OF FILTERING SLIMES.

, APPLICATION FILED 00122 1913. 1 1G 55: ,3 Patented June 16, 1914.

3 SHEETSSHEET 2.

G. BUTTBRS.

PROCESS OF FILTERING SLIMES.

APPLICATION FILED 0033.22, 1913.

1,100,223, v Patented June 16,191 l 3 SHEETS-SHEET 3.

WITNESSES lNVEA/TOR UNITED STATES PATENT OFFICE.

cmtfitns BUTTERS, or OAKLAND, cALrronm'A.

rraocnss or surname sLIMEs.

menses.

Specification of. Letters fatent.

1913. Serial No. 796,595.

'0 all whom it may concern 3 Be it known that I, Gunner's Bo'r'mns, acitizen of the United States, and a resident of @akland, county ofAlameda, State of California,- have invented certain new and usefillImprovements in Processes of Filtering Slimes, of which the. followingis aspecification'.

The object of my invention is to shorten the time taken for a cycle ofoperation in the process of filtering valuable compounds,

I such as sliines', which result from the well known cyanid process oftreating ores.

Another object of my invention is to lower the costof filter leaveswhile at'the same time increasing their life and value.

In abstracting the values from slimes one of the most d-ifiicult andtroublesome problems is to dislodge reliably and within an economicaltime, the slime cake from the surface of the filtering medium after thefilter process has been completed, without injurihg the filter surfaceof the leaf.

lit has been the practice heretofore to dislodge slime cakes by airpressure placed on the interior of the leaves while suspended in theair, or this has been accomplished in some cases by water under pressurebeing passed through the filter medium in a direction reverse to that ofthe filtrate. It has been supposed heretofore that to dislodge the cakereliably and within an economical time, pressure was necessary whet-herof air, water or other fluid in the dislodging step, and specialprecaution has sometimes been taken to get a uniformly thick, cohesiveand resistant cake deposit such that the fluid under pressure mightdislodge it as anen tiret-y and make it unnecessary to use additionalmeans' -to dislodge the cake co'mpletely. By my process suchuniformity'of the cake is of no importance at all ,to the cakedislodgment, and consequently the filtering operation may be moreeconomical.

If notable internal pressure is put on a leaf for cake-dislodgmentpurposes, means must be provided to prevent distension or ballooning ofthe filter medium. Various means have been devised to :this end, all ofwhich have added to the difliculty of cakedislodgnrent. As a matter ofpractice, too, it is found that all such means are a hindrance to properand economical operation; further, they shorten the life of the leaves,but have been regarded as indispensable when former practicable methodsof cakedislodginent have been used he efiiciency of the leavesheretofore used Is low, first, because a considerable amount of thefilter surface of the medium is obstructed by the means used to preventballooning, andsecond, because of stitching the media together or bybolting strips onto the outside of the leaf to prevent ballooning,comparatively large holes are made in the media. more liable toruptureunder internal pressure. thus shortening their life.

I have discovered that pressure is unnecessary to reliablecake-dislodgment within an economical time, and that complete successcan be attained by saturation of the entire area of the filter medium.It is found 111 practice that these cakes have unusual adhesion andcohesion, and that when a, cake 1s formed on each side of a filter leafthey are not easily dislodged. Due to the great cohesion of the cake itis very important that the upper part, as well as the other parts, ofthe filter medium be saturated in the dislodging step, as it is foundthat the adhesion of the cake to the medium is greatly lessened, andthat the time for dislodgment is materially shortened thereby. This hasnot been attained in leaves hereto,- fore constructed because theycontained enough air to prevent water reaching the top- .part thereofeven when admitted under pressure. This was true in site of the fact,that the leaf might be un er vacuous conditions at the time the waterWas first admitted. I have therefore devised, a leaf which may or maynot haveinternal pressure applied thereto during the dislodging step,but I do not depend upon internal pressure to dislodge the cake, since bmy invention the cake can be dislodged without internal pressure. It isunderstood that the cake may be, and preferably is, dislodged while theleaf is submerged in wash water. This means that there will beconsiderable hydrostatic pressure on the outside of the leaf. This is ormay be balanced by the hydrostatiopressure on the inside of the leaf.When internal pressure also is used itneed not be high. A

The principal advantages of my improved leaf over previous ones are:first, under otherwise similar conditions itdislodges its such as stripsdown the sides;

Also, theseholes make the media a p Patented June 16, 1914. commapplication mod ma as, 1915, Serial No. 769,779, Divided and thisapplication filed October 22',

vent ballooning,

cake in a shorter time; and secondly, it is a more efiicent filter. Theabove advantages are attributed to the fact that substantially theentire surface of the leaf is saturated during the dislodging stepbecause the air is permitted to escape through the relief valve and asthere need never be high internal pressure no means are required toprevent ballooning; therefore, the surface may be smooth, being clear ofall manner of bracing, stitching or other surface-roughening means whichhave heretofore been necessary to preand consequently the cake is moreeasily dislodged.

Other advantages will be apparent from the following detaileddescription taken in connection with the accompanying drawings, inwhich-.-

Figure 1 shows a diagrammatic plan view of a general layout showin aclean water source and piping for supp ying the water to the leaves;Fig. 2 is a side elevation of the devices shown in Fig. 1; Fig. 3 is aplan of a portion of a vat wlth several leaves therein; Fig: 4 is a viewof a leaf embodying my invention; Fig. 5 is a plan view of a reliefvalve; and Fig. 6 is a section of a relief valve. i

In Fig. 1 are shown a plurality of vats 1 in which the leaves 2 areplaced as shown in Fig. 3. These leaves are connected with the cleanwater source 3 by means of the piping 4 and 5 through any suitableconnection 6 such as a rubber elbow. In order that the Water may reachall the leaves quickly the pipe 5 is arranged along the top of the vatsand is connected with the pipe 4 from the --water supply by means ofrisers 7 In pipe 4 are placed va cs8 and 9 so that a portion of the pipe4 and the pipe 5 may be used both for conducting the filtrate from theleaves during the filtering operation, and also for supplying the cleancake-dislodging water at the proper time. The pum 10 is shown connectedwith the pipe 4 or the purpose of creating a vacuum within the leavesduring the filtering operation.

When it is desired to begin the filtering operation valve 8 is closedand pump 10 started to decrease the pressure within the filter leavesand thereby draw a filtrate through and form a cake on the surface ofthe filter medium. been formed, it may be treated in well known wayswith barren solution and then with wash water, and it is then ready tobe dislodged. The valve 9 is then closed and valve 8 is opened therebyrun into the leaves from the tank 3 through the piping 4, risers 7,pipes 5 and 6, thus filling the leaves and causing the cakes, withinfour or five minutes, to drop. The air contained in the leaves isdischarged through the relief-valves 11. The thick slime is then run outfrom the bottom of the When suflicient cake haspermitting the watertovats into the run-way 12, and thence to the slime-pit. The vats may beproperly supported by any convenient means such as the pillars 13 andI-beams 14, shown in Fig. 4.

As shown in Fig. 4 the leaf comprises a frame having members 15, 16, 17and 18, preferably of tubing. Over this frame is secured a filter medium19 of canvas or other suitable material. Inside the filter-leaf is afibrous filler 20 preferably of cocoa mat, for holding the sides thereofapart when vacuum is created within the leaf. The lower frame member 15is perforated or slotted along its upper side and is connected to avacuum pump 10, or other pressure-decreasing means through the righthandend member 16 and the connection 6 which may be of rubber or othersuitable material. The filtrate is removed from the leaf b means of thepump 10. The left -hand frame member 17 is plugged by any suitable meanssuch as a wooden plug shown at 21 in Fig. 1. The top frame member 18 iserforated or slotted along its lower side and to this member is attachedthe relief-valve 1 1. This member is also plugged as shown at 28, and isrigidly connected to the right hand end member to make a ri id framestructure. It is not necessary t at the relief valve be connected to theframe member, but this arrangement is preferred and-it is so illustratedin the drawin s. The pipe 22 connectin the valve to the eaf may be ofany suitable length. The relief valve 11 should be connected to theupper portion of the leaf in order to allow the escape of air, but itmay be connected to any point of the leaf to prevent internal pressureif this aloneis desired.

The preferred form of relief valve is shown in detail in Figs. 5 and 6,but it is obvious that other kinds of valve may be used provided itallows exit but prevents entrance of air. The valve hereafter describedis by way of example only and must not be considered as limiting myinvention. As shown in Figs. 5 and 6, the relief-valve consists of apipe-coupling 23 around -which is securely clamped a rubber tube 24 theupper end of which acts as a valve seat. This tube is clamped around thecoupling 23 by a band25 in any well known manner. Arranged to 005 eratewith the seat 24 is a ball 26 of rub er. For the purpose of confiningthe movement of the ball, guards 27 are placed around same, as clearlyshown in the drawing.

' It will be readily understood that by the use of a valve of the kindabove described, the entrance of air will be entirely prevented whenvacuum is created within the leaf, thereby not interfering in any waywith the filtering properties of the leaf. As soon as vacuum isrelieved, the elasticity of the seat will push the ball up, and due tounavoidable irregularities, small passages will exist between the balland its seat sutlicient to allow the escape of whatever air remains inthe leaf as water is admitted thereto. By this arrangement the air maybe easily displaced by water when the latter is admitted to the leaf sothat it can saturate the entire surface of the filter inedia and cause arapid dislodgment of the cake. The water for this purpose is suppliedfrom any suitable supply 3 through the connection 6, frame member 16 andperforated frame member 15 into the bottom of the leaf.

In Fig. 3 is illustrated a series "of leaves 2 placed on the sides of avat, 1.

The operation of my device is as follows: The leaf is completelysubmerged, care being taken not to allow slimes to enter therelief-valve. Suction is applied to the interior by any means, such as avacuumpump, and the filtrate is carried off by the pressure-decreasingmeans. As soon as the internal pressure is decreased the reliefvalvecloses tight so as to completely prevent the entrance of air. Thesuction is continued until a: cake of pro er thickness is deposited onthe filter sur ace. This cake may then be variously treated with barrensolution and wash water, and then the vacuum is turned off and water-isconducted into the bottom frame member 15, the leaf being stillsubmerged, or not, as desired. As

and carries with it all entrapped air from I inside the leaf andconsequently more effectively saturates the entire filter surface.

One advantage of having the water under pressure is that the air isexpelled quickly and also the leaf is filled up with water quickly. Whenthe "filter surface is saturated the cake is automatically and quicklydislodged and the surface of the filter medium is cleansed and ready foranother cycle. The matter claimed in the present application is dividedout of my application, Serial No. 769,779, filed May 26, 1913, in whichthe claims are directed to the apparatus.

Having described my invention, what I claim as new and desire to secureby Letters Patent, is g 1. The process of d-islodging slime cakes fromfilter cloths, whichconsists in saturating without pressuresubstantially the entire surface of the cloth while the cake is thereon.

a cake is formed, and subsequently admitting water' into said leaf whileremoving the air therefrom so as to saturate substantially the entiresurface of the filter me'-' dium to dislodge the cake.

.3. The process of filtering slimes, which consists in submer 'ng afilter leaf in the is formed, and subsequently admitting water withoutpressure into said leaf while removing the air therefrom so as tosaturate said medium to dislodge the cake.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

- CHARLES BUTTERS.

Witnesses:

NEWTON A. Bunenss,

. EDWIN Susan.

slimes, creating di erence of pressure on the i sides of the medium ofsaid leaf until a cake

